1. Field of the Invention
The present invention relates to a fuel injection apparatus for an internal combustion engine in which an electroexpansive actuator is arranged so as to enable precise and rapid response to an electric signal.
2. Description of the Prior Art
Most conventional prior art fuel injection apparatuses for internal combustion engines incorporate solenoid actuators. Such solenoid actuators generally have response times larger than 10 ms, which impedes engine performance and fuel efficiency.
In order to improve the response time, recent fuel injection apparatuses have been equipped with electroexpansive actuators. While such electroexpansive actuators offer faster response times, they suffer from the disadvantage of small needle lift. Accordingly, they are not suited for large injected fuel amounts.
In addition, it was impossible to continuously control the fuel injection amount in accordance with the driving frequency in a spark-ignition engine. In a diesel engine, it was impossible to compensate for a delay of compression ignition.